1. Field of the Invention
The present invention relates to a synchronous reluctance motor and a compressor having the same, and more particularly, to a synchronous reluctance motor capable of enhancing a reliability thereof when rotated by decreasing a length in an axial line direction extending from a supporting portion without reducing a stacked thickness in the axial line direction, and a compressor having the same.
2. Description of the Background Art
A synchronous reluctance motor is rotated in a synchronous speed by a reluctance torque due to an inductance difference between a D-axis inductance and a Q-axis inductance. The synchronous reluctance motor is being increasingly used owing to a low fabrication cost, a high reliability, and a permanent lifespan thereof.
As shown in FIG. 1, a hermetic compressor comprises: a case 10 having a hermetic receiving space therein, a compression unit 21 installed in the case 10 for compressing a fluid such as a refrigerant, etc.; and an electric motor 31 having a rotation shaft 37 connected to the compression unit 21, for providing a driving force to the compression unit 21.
A suction pipe 11 for sucking a fluid and a discharge pipe 12 for discharging a compressed fluid are coupled the case 10, respectively. An accumulator 15 for sucking a fluid of a gaseous state is connected to the suction pipe 11.
The compression unit 21 comprises a cylinder 23 having a compression space therein; an upper bearing member 25 and a lower bearing member 27 coupled to an upper surface and a lower surface of the cylinder 23, respectively, for rotatably-supporting the rotation shaft 37; and a roller 29 arranged in the cylinder 23 so as to be eccentrically-movable, for compressing a refrigerant.
The electric motor 31 comprises a stator 33 fixed to inside of the case 10, and a rotor 35 arranged so as to be rotatable with respect to the stator 33. The rotor 35 comprises a rotation shaft 37 having an eccentric portion 38 at a lower portion thereof; and a rotor core 39 rotatably coupled to the rotation shaft 37. The eccentric portion 38 serves to eccentric-movably couple the roller 29. A balance weight 40 is respectively coupled to an upper end and a lower end of the rotor 35.
However, in the related art hermetic compressor, the electric motor 31 is arranged at an upper side of the compression unit 21, and a lower portion of the rotation shaft 37 is supported by the upper bearing member 25 and the lower bearing member 27. Accordingly, the length L1 extending from the upper end of the upper bearing member 25 along the axial line direction is increased. As the result, the upper portion of the rotor 35 spaced from the upper bearing member 25 is much vibrated in a horizontal direction with respect to the axial line, and it is difficult to obtain the reliability of the motor when the rotor is rotated in a high speed. Especially, in case of a synchronous reluctance motor having a stacked thickness of the rotor 35 increased than that of an induction motor or a BLDG motor, the length L1 extending from the upper end of the upper bearing member 25 along the axial line direction is increased. Accordingly, it becomes more difficult to obtain the reliability of the synchronous reluctance motor.